1. Field of the Invention
The present invention relates to an organic electronic device, and particularly, to a photocurable pressure-sensitive adhesive composition used to encapsulate an organic electronic device (OED), an adhesive film formed thereof, and a method of manufacturing an OED.
2. Discussion of Related Art
An OED refers to a device including an organic material layer generating the exchange of charges using holes and electrons, and may include a photovoltaic device, a rectifier, a transmitter and an organic light emitting diode (OLED).
An OLED, which is a representative OED, has less power consumption and a higher response speed than conventional light sources, and is preferable as a thin display device or light source. In addition, the OLED has excellent space utilization, and thus is expected to be applied in various fields including all kinds of portable devices, monitors, notebook computers and TVs.
To extend compatibility and use of the OLED, the most important problem is durability. Organic materials and metal electrodes included in the OLED are very easily oxidized by external factors such as moisture, and a product including the OLED is very sensitive to environmental factors. Therefore, various methods of preventing penetration of oxygen or moisture from an external environment have been suggested.
A large-scale element has a limitation in an edge sealing method due to the deterioration of the element caused by the lack of mechanical strength and the decrease in efficiency of heat emission. Generally, a UV edge sealing or frit method in combination with a getter additionally uses a heat-curable/visible ray-curable filling adhesive, which thus makes a process complicated, resulting in a further increase in cost.
In addition, although the edge sealing may improve mechanical strength and ensure a moisture barrier property due to the type of filling, the edge sealing may be difficult to apply to a flexible display. The heat-curable entire surface filler is necessarily cured at low temperature to avoid damage to an element. However, since the heat-curable filler has a short pot life to be cured at low temperature, processability is degraded. The visible ray-curable filler has difficult curing conditions and many limitations in selection of a material, compared to a UV-curable filler.
In Korean Patent Application Publication No. 2009-0121271, an adhesive method using a liquid-state adhesive resin composition containing a heat-curable resin, a latent curing agent, a photopolymerizable resin component having an unsaturated group and a visible-ray polymerization initiator is disclosed. Since the liquid-state adhesive resin composition is pre-cured by visible-ray irradiation to an entire surface of a substrate including an element and then cured by heat, the organic light emitting element may be damaged.